ANNALS OF CLINICAL AND LABORATORY SCIENCE, Vol. 12, No. 4 Copyright © 1982, Institute for Clinical Science, Inc.

Diagnosis of Abnormalities in Gonadal Development BERNARD GONDOS, M.D. Department of Pathology, University of Connecticut, Farmington, CT 06032

ABSTRACT The role of the clinical laboratory in the diagnosis of abnormalities in gonadal development is reviewed, beginning with a description of the normal differentiation of the ovary and testis and the major types of disorders encountered. The conditions are classified as resulting from abnormal go­ nadal differentiation, defective endocrine function or excessive endocrine activity. Germ cell neoplasms are also reviewed. Laboratory procedures utilized in evaluation of gonadal abnormalities include cytogenetic, hor­ monal, and histopathologic studies. Standard procedures are described as well as newer methods which have undergone increasing use in recent years and other specialized procedures which are under investigation for possible clinical application.

Introduction tors may all play a role in the development of structural and functional abnormalities The role of the laboratory in the diagno­ of gonadal differentiation. As a result, sis of abnormalities in gonadal develop­ classifications of intersex disorders and ment is particularly important. Because of abnormalities of hormone production are the many varieties of such disorders and often confusing. their complex pathogenesis, the types of The present report reviews the labora­ laboratory tests utilized are quite varied. tory diagnosis of disorders of gonadal de­ The applications and significance of these velopment, beginning with a consider­ tests should be clearly understood, since ation of normal gonadal differentiation proper utilization and evaluation may be and a brief summary of the main categor­ critical in determining gender role assign­ ies of abnormalities. Clinical aspects are ment and the need for specific forms of considered only insofar as they relate to therapy. the selection and evaluation of laboratory The complexity of this area is a result of procedures, and detailed information in the many etiologic and pathogenetic fac­ this area should be sought elsewhere. The tors involved. Genetic, chromosomal, emphasis in this review is on a description anatomic, histologic, and hormonal fac- of tests currently available as well as 276 0091-7370/82/0700-0276 $01.80 © Institute for Clinical Science, Inc. ABNORMALITIES IN GONADAL DEVELOPMENT 277 newer methods which have begun to be tial regions,46 associated with the onset of used in recent years or are still under in­ testosterone production.47 This is fol­ vestigation for possible clinical application. lowed by growth of the Wolffian ducts, lengthening of the urogenital distance Gonadal Differentiation fusion of the labioscrotal swelling, and closure of the urethral groove. Differenti­ The gonads arise as outpouchings into ation of the Wolffian ducts into the the coelomic cavity from the genital ridge epididymis, vas deferens, and seminal early in embryonic development. Germ vesicles occurs under the control of testos­ cells migrate to the developing gonads terone, while its reduced form, dihydro­ from the yolk sac region and increase in testosterone (DHT), regulates the differ­ number by mitotic division. While the go­ entiation of the external genitalia.63 nads are still sexually undifferentiated, At mid-gestation, the Leydig cells un­ the Wolffian and Mullerian ducts begin dergo regression,58 and there is a corre­ development, the urogenital sinus forms, sponding fall in testosterone production.53 and the urogenital tubercle, urethral fold, The testis continues to rest against the and groove appear. anterior abdominal wall and the tip of the Genetic sex is established at the time of gubemaculum projects into the scrotum. fertilization, but sexual differentiation of The testis descends into the scrotum dur­ the gonads becomes evident only at the ing the third trimester, and there is growth end of the second month of gestation with of the external genitalia. the development in the male of testicular In the newborn period, there is a cords. The establishment of testicular dif­ transient redifferentiation of Leydig ferentiation has generally been associated cells31 and rise in testosterone produc­ with the presence of the Y chromosome, tion.19 After a few months the levels of but recent evidence suggests that H-Y serum testosterone fall and remain low antigen, a cell surface component that is until the onset of puberty.3,64 Similarly, present in males of all mammalian spe­ the interstitial tissue consists principally cies, correlates more closely with the for­ of undifferentiated mesenchymal cells mation of a testis than the presence of a Y throughout childhood. Germ cells are of chromosome.60 prespermatogenic type, and Sertoli cells of adult type are not present during this T e s t is period.28 Maturational changes in Sertoli Testicular differentiation occurs at six cells, including formation of occlusive in­ to seven weeks gestation with the forma­ tercellular junctions responsible for the tion of cords of primitive germ cells and blood-testis barrier, occur at the time of Sertoli cells and the development of the onset of spermatogenesis at puberty. tunica albuginea. The cytoplasm of Ser­ toli cells includes organelles associated O va ry with protein production, and these cells are responsible for the production of anti- Ovarian differentiation can be pre­ Miillerian hormone, a glycoprotein pres­ dicted early in embryonic development ent in the fetal seminiferous cords.36 Re­ by the presence of Barr bodies indicating gression of the Mullerian ducts begins more than one X chromosome. However, shortly after the appearance of the fetal distinctive structural changes are not evi­ Sertoli cells. dent until the onset of meiosis and the At eight weeks, Leydig cells with char­ beginning of follicle formation. After a acteristic ultrastructural features of ster­ period of extensive mitotic activity in­ oid-secreting cells appear in the intersti­ volving oogonia, the ovarian germ cells 278 GONDOS enter meiosis at 11 to 12 weeks. Numer­ estradiol and estrone are low throughout ous oocytes can be seen in various stages childhood and increase only during the of meiotic prophase throughout the ovar­ initial stages of breast growth.33 Urinary ian cortex during the remainder of fetal excretions of estrone, estradiol, and es- development and into the neonatal triol increase with sexual maturation. An­ period.58 The first follicles begin to form drogen activity present in young girls is during the fifth month of gestation, as in­ considered to be principally of adrenal dividual oocytes become surrounded by origin, although ovarian hilar cells have granulosa cells. the capacity for androgen production. During the early developmental period, ultrastructural features associated with Types of Disorders steroidogenic activity can be seen in scat­ tered interstitial cells28 and histochemical Classifications of abnormalities in go­ evidence of steroidogenic activity can be nadal development have been based on found in granulosa cells and interstitial phenotypic appearance, clinical manifes­ cells.6 Recent observations indicate that tations, genetic factors, anatomic charac­ steroid conversions can occur in the ovary teristics, biochemical defects, and go­ early in fetal development,22 but demon­ nadal abnormalities. The most successful stration of a significant endocrine role for classifications have stressed pathogenetic the fetal ovary remains to be established. considerations.18,20’29’35,49 As indicated in Differentiation of theca interna and for­ table I, the disorders can be grouped as mation of medium-sized and large folli­ follows: (1) abnormalities of gonadal dif­ cles occur during the third trimester and ferentiation, indicating structural prob­ neonatal period. Large follicles can be lems appearing early in development; (2) seen in newborns and infants. defects in endocrine function, occurring Ovarian production of hormones is min­ during both fetal and postnatal develop­ imal in the neonatal period. Plasma ment; (3) excessive endocrine activity, manifested generally by precocious developmental changes in infancy and TABLE I childhood. A fourth group, germ cell Classification of Gonadal Disorders neoplasms, not necessarily a result of ab­ in Newborns and Infants normal gonadal development, is included because of similarities in clinical manifes­ Abnormal Gonadal Differentiation tations and because developmental as­ Sex chromosome disorders Autosomal abnormalities pects may play an important role in cer­ True hermaphroditism tain gonadal tumors. Testicular regression syndrome Germ cell aplasia The list of disorders is general and not Cryptorchidism comprehensive. Abnormalities which be­ Defective Endocrine Function come clinically evident only at the time of Androgen insensitivity Defects in testosterone synthesis puberty and afterward are not included. 5a-Reductase deficiency Emphasis is placed on those disorders Leydig cell hypoplasia Hypogonadotropic hypogonadism which can be diagnosed in newborns and Defective Sertoli cell function infants.

Excessive Endocrine Activity Leydig cell hyperplasia Ab n o r m a l G o n a d a l D ifferentiation Leydig cell tumor Ovarian follicle cysts Granulosa cell tumor Abnormalities in this group are gener­ Hilar cell hyperplasia ally a result of chromosomal disorders. Germ Cell Neoplasms Most of these are related to the sex chro­ mosomes, but autosomal abnormalities ABNORMALITIES IN GONADAL DEVELOPMENT 279 may also affect gonadal differentiation. stances does not involve the laboratory. The sex chromosome disorders include a However, because of the increased inci­ great variety of possible defects including dence of germ cell neoplasms in unde­ additional X or Y chromosomes, a single X scended testes, the pathologist may be chromosome (Turner’s syndrome), mosai­ called upon to evaluate such specimens cism, and structural abnormalities.23 Ge­ and should be aware of the histologic ap­ netic factors may also be involved in the pearance of cryptorchid testes at different absence of detectable karyotypic abnor­ ages. In addition, a recently described malities. True hermaphroditism, indicat­ condition of intratubular germ cell hyper­ ing a condition in which both ovarian and plasia, a precursor to germ cell neoplasms, testicular elements are present, may be has been observed in undescended and associated with chromosomal abnormali­ atrophic testes.55 ties, but most cases demonstrate a 46,XX karyotype indistinguishable from a nor­ mal female. The term, gonadal dysgene­ D e f e c t iv e E n d o c r in e F u n c t io n sis, has been used for many of the Since active hormone production oc­ chromosomal disorders but has also been curs in the fetal testis and not the fetal applied to disorders resulting from abnor­ ovary, abnormalities in this group are malities of endocrine function, thus cov­ generally restricted to genetic males. ering a range of pathogenetic categories. However, because of defective androgen Developmental abnormalities not nec­ production, the individuals are often essarily related to genetic or chromosomal phenotypic females. Major disorders in defects also occur. Testes may be absent, this group are caused by gene-related de­ rudimentary, or abnormally formed in in­ fects in hormone synthesis or action and dividuals with normal 46,XY karyotype. A may have a familial pattern. In other con­ variety of terms, including gonadal agene­ ditions, the cause is not known. sis, anorchia, and Swyer’s syndrome, have The most well known abnormality in been used for such abnormalities. The this group is the so-called testicular femi­ term, testicular regression syndrome, has nization syndrome. A preferred term is been suggested to designate these dis­ androgen insensitivity syndrome. The de­ orders14,16 and appears to be most fect is not in the gonad itself but at the appropriate in indicating the probable level of target cells in their lack of re­ pathogenesis. sponse or resistance to androgen action. Germ cell aplasia (Sertoli cell-only syn­ The individuals have female-type exter­ drome, del Castillo syndrome) is a cause nal genitalia and breast development in of male infertility generally diagnosed in spite of having a normal male 46,XY the adult period, but potentially detect­ karyotype and active Leydig cell function. able at an earlier age. The condition is The androgen insensitivity of target tis­ usually idiopathic and the cause un­ sues is evidently an X-linked disorder.44 known. Some cases can be attributed to More specifically related to testicular radiation injury or other causes of germ function are abnormalities of testosterone cell degeneration. In most cases, there is synthesis. These involve defects in enzy­ probably a developmental defect in germ matic activity at one of five different steps cell formation, migration, or differenti­ in the steroidogenic pathway. The result­ ation or a failure in germ cell develop­ ing deficiency in testosterone formation is ment because of excessive degeneration. associated with clinical manifestations Cryptorchidism, reflecting a develop­ suggesting such terms as incomplete mental abnormality in testicular descent, testicular feminization. As has been is diagnosed clinically and in most in­ pointed out, these disorders should be 280 GONDOS classified in terms of the specific enzy­ pretation had been reported in the past. matic defect which can be determined by Further support comes from a recent re­ appropriate laboratory analysis.24 port describing a patient with a single Another related condition involves a uterine horn and normal Fallopian tube defect in 5a-reductase activity which is on one side and correlation of the appear­ responsible for conversion of testosterone ance of Sertoli cells in the ipsilateral go­ to DHT.32,62 This is associated with nor­ nad with the morphology of the internal mal testosterone levels so that the internal genitalia.5 genital tract structures develop normally, but the deficiency in DHT results in ab­ E x c e s s iv e E n d o c r in e A c t iv it y normal formation of external genitalia. Al­ though this condition is manifested clini­ Most cases in which excessive hor­ cally at the time of puberty, because of the monal activity results in genital tract ab­ strong familial pattern it can be suspected normalities in infants and children are not and diagnosed earlier by hormonal stud­ a result of intrinsic gonadal disorders. For ies, so that a decision can be made in re­ example, the appearance of ambiguous gard to gender assignment. genitalia in a newborn female is most Deficiency in testosterone production likely related to congenital adrenal may be a result of Leydig cell hypoplasia.8 hyperplasia, maternal steroid hormone The paucity of Leydig cells is in contrast administration, or virilizing ovarian tu­ to the abundance of Leydig cells seen in mor. Precocious puberty developing in the conditions previously described. This young children is most commonly idio­ condition, as would be expected, is associ­ pathic or neurogenic in origin. A few ated with abnormal differentiation of in­ types of disorders are related to abnormal ternal and external genitalia. gonadal function and these must be Hypogonadotropic hypogonadism oc­ distinguished from the other types in or­ curs in both males and females. The ef­ der to determine proper evaluation and fects on gonadal function are secondary to treatment. defective pituitary gonadotropin produc­ In males, evidence of precocious sexual tion. This is readily diagnosed by finding development may appear in the first few low luteinizing hormone (LH) and follicle years of life as a result of excessive Leydig stimulating hormone (FSH) levels. In cell activity and consequent elevated tes­ some cases, isolated gonadotropin defi­ tosterone levels. This may be a result of ciency has also been found. The abnor­ hyperplasia or tumor. Leydig cell hyper­ malities in gonadotropin production may plasia, which is bilateral, must be dis­ be related to intrinsic pituitary defects or tinguished from adrenal abnormalities. to secondary effects of abnormal hypotha­ Measurement of adrenal androgens and lamic function. The role of hypothalamic testing for dexamethasone suppression releasing factors in regulating pituitary and gonadotropin stimulation are partic­ activity requires special investigation in ularly helpful in this regard. Leydig cell these conditions. tumors in this age group are generally With the recognition that Sertoli cells benign.7 are responsible for producing the sub­ In females, ovarian follicle cysts or stance that causes regression of the granulosa cell tumors may account for evi­ Mullerian ducts, it could be postulated dence of precocious puberty. It should be that in 46,XY individuals with persistent pointed out that follicle cysts are fre­ uterine and tubal structures defective quently found in young children and their Sertoli cell function might be involved. presence in a case of precocious puberty Several cases supporting such an inter­ does not necessarily indicate an etiologic ABNORMALITIES IN GONADAL DEVELOPMENT 281 relationship. This is borne out by the ob­ though it is actually not a germ cell tumor servation that removal of such cysts often but rather an abnormality of gonadal dif­ fails to reverse the symptoms. Juvenile ferentiation that may evolve into a germ granulosa cell tumors are only rarely cell neoplasm. Gonadoblastomas gener­ found in infants, generally appearing at an ally occur in phenotypic females with sex older age,52 and therefore would be an chromosome disorders, often with mosaic unlikely cause of precocious puberty at an patterns and often, but not always, includ­ early age. Hilar cell hyperplasia with pro­ ing a Y chromosome.51 The important con­ gressive hirsutism resulting from ele­ sideration in the evaluation of such pa­ vated testosterone production has been tients is that the predilection to develop reported in a patient with gonadal germ cell neoplasms shows a strong corre­ streaks.38 lation with the presence of a Y chromo­ some.50 This is generally true of individ­ uals with sex chromosomal disorders. It G e r m C e l l N e o p l a s m s has therefore been suggested that in pa­ The most common testicular tumor tients with a Y chromosome and abnormal found in infants is the yolk sac tumor. This gonadal development, the gonads should is a germ cell derivative representing an be removed prior to puberty when there is extraembryonic line of differentiation. It an appreciable rise in the development of is also known as endodermal sinus tumor, malignant tumors.42 which is the more frequent designation for the identical tumor occurring in the Laboratory Diagnosis ovary. In the testis, tumors diagnosed at The indications for performing specific an early age, that is under two years, have laboratory tests will depend on the clini­ a relatively good prognosis.7 This is in cal findings and evaluation. In some contrast to the ovary in which the tumors cases, a single procedure may establish behave very aggressively,52 although in the correct diagnosis. However, in most recent years use of combination chemo­ instances of abnormality of gonadal func­ therapy has greatly improved survival. tion, multiple tests will be required. Se­ The tumors produce large amounts of lection and interpretation will depend on alphafetoprotein which can be identified a thorough knowledge of the consider­ in blood and urine by radioimmunoassay ations discussed above. Currently avail­ as well as in the tumor tissue by immuno- able tests (table II) generally fall into histochemistry. three main categories, including cyto­ Another germ cell tumor occurring in genetic, hormonal, and histopathologic young boys is the teratoma, a neoplasm studies. composed of tissues from all three germ layers. This tumor also shows a sharp sex difference in clinical behavior. In males C y t o g e n e t ic St u d ie s in the childhood period teratomas are Initial screening is done with a buccal generally benign without evidence of me­ smear to detect the presence or absence of tastasis, while in girls teratomas are fre­ Barr bodies, correlating with the number quently highly malignant. This situation of X chromosomes. This is a simple proce­ becomes reversed in adults. The reason dure which may be helpful but is gener­ for the discrepancy may relate to the dif­ ally of limited value in most diagnostic ference in timing of oogenesis and problems. spermatogenesis.17 Procedures to demonstrate Y chromo­ The gonadoblastoma is often included some fluorescence are also available. in discussions of germ cell neoplasms, al­ These can indicate the presence or ab­ 282 GONDOS sence of the Y chromosome as well as pos­ human chorionic gonadotropin (hCG) sible abnormalities. stimulation of testosterone production. The definitive procedure for detection Dexamethasone suppression of androgen of chromosomal disorders is the karyotype levels will distinguish between adrenal analysis which will demonstrate the pre­ and testicular origin. Steroid receptor cise chromosomal pattern. Absent or studies are also important, for example, in additional chromosomes, structural ab­ the androgen insensitivity syndrome, as normalities, and abnormal marker chro­ well as in other conditions. mosomes can be identified. This proce­ Gonadotropin levels determined by dure is most frequently performed on radioimmunoassay, including LH, FSH peripheral blood lymphocytes. Where in­ and hCG, are important in evaluating dicated, karyotype studies should also be problems in gonadal development. Spe­ done on other tissues, including skin cific identification of the polypeptide hor­ fibroblasts and both gonads. mones is facilitated by the analysis of beta-subunits. In addition to the gonado­ H o r m o n a l St u d ie s tropins, other pituitary hormones such as prolactin and growth hormone have been Vaginal cytology can be used as a implicated in the regulation of gonadal screening test for abnormal estrogen pro­ maturation,45 although their significance duction in young girls. As with the buccal in this regard remains to be determined. smear, this is a simple procedure of rela­ Some question has also arisen recently tively limited usefulness. In difficult di­ regarding the biological relevance of agnostic problems, specific hormonal as­ gonadotropin radioimmunoassays in the says should be performed. developmental period. It has been found, Steroid hormone analysis by radioim­ for example, that there is considerable munoassay is available for a number of discrepancy between radioimmunoassay substances. Testosterone and estradiol and bioassay determinations of FSH and levels are the most specific indicators of LH in the prepubertal period.39 The bio­ gonadal secretion, but numerous other assay procedures are discussed later. steroids involved in biosynthetic conver­ As previously described, radioimmuno­ sions and metabolic breakdown may also assay for alphafetoprotein is particularly be determined as indicated. Serum and useful in the diagnosis and monitoring of urine determinations are most frequently patients with yolk sac tumors. employed, but other fluids and tissue frac­ tions can also be analyzed. Among the most frequent diagnostic H istopathologic St u d ie s problems involving steroid hormone anal­ ysis is the distinction between gonadal In most of the abnormalities described, and adrenal origin. This is particularly the the diagnosis will be established by clini­ case in abnormalities of sexual differenti­ cal findings, cytogenetic analysis, and ation. Familiarity with the different pat­ hormonal studies. Occasionally, biopsy is terns of steroid metabolism in the differ­ required for specific confirmation, to ex­ ent endocrine organs is obviously critical. clude neoplasm or in certain primary go­ Pregnanetriol levels will be of particular nadal defects.65 In the case of neoplastic value in indicating adrenal hyperfunc- disorders, the pathologist plays a key role tion. In addition to direct hormone meas­ and therefore should have a thorough un­ urements, provocative tests are especially derstanding of germ cell tumors, endo­ useful. Testicular capacity, specifically crine tumors, and other types of neo­ Leydig cell function, can be assessed by plasms occurring in the ovary and testis of ABNORMALITIES IN GONADAL DEVELOPMENT 283 infants and children. Several reviews on TABLE I I this subject are available.7,52,56 Laboratory Diagnosis of Abnormalities in The use of electron microscopy should Gonadal Development* be considered in difficult diagnostic prob­ Cytogenetic Studies lems. Ultrastructural examination may be Buccal smear H-Y antigen critical in evaluating developmental de­ Y fluorescence Amniocentesis fects in which subtle distinctions in stages Karyotype analysis Hormonal Studies of germ cell and Sertoli cell maturation Vaginal cytology Steroid binding proteins may be difficult to assess by routine light Steroid determinations Gonadotropin releasing Gonadotropin radio- hormone microscopy.28 Similarly, determination of immunoassay Gonadotropin bioassay Leydig cell differentiation is best evalu­ Alphafetoprotein Anti-Müllerian hormone Receptor studies Meiosis regulating ated by electron microscopic analysis. Al­ substances though the use of electron microscopy in Histopathologic Studies studying gonadal neoplasms is not re­ Light microscopy Immunoperoxidase quired in most cases, such studies have Electron microscopy Freeze-fracture greatly enhanced understanding of the ‘Standard procedures are indicated on left, newer morphologic characteristics and patho­ methods on right. genesis of these tumors. Application of electron microscopy in cases of abnormal gonadal maturation should receive care­ ful consideration on a selective basis. tories. Utilization of H-Y antigen analysis is considered an essential part of the eval­ uation in patients with gonadal develop­ Recent Developments mental disorders of uncertain origin. Newer methods developed in recent Amniocentesis has now become estab­ years have added special capabilities in lished as a reliable, clinically useful evaluating disorders of gonadal develop­ procedure, as performed by those pos­ ment (table II). Some of these methods are sessing the required expertise.25 As a re­ available for clinical application in certain sult, karyotype analysis can be done on laboratories and utilization of these proce­ amniotic fluid specimens, allowing diag­ dures may be essential in the diagnostic nosis of chromosomal disorders during fe­ work-up of specific cases. Other methods tal development. have been used principally in the re­ search laboratory but offer promise for ap­ H o r m o n a l M e t h o d s plication in the clinical laboratory. Addi­ tional methods are described which at Steroid binding protein assays have present are restricted to experimental pro­ been applied in experimental studies and tocols; however, they are included be­ have been found to provide important cause they offer insight into possible mod­ new information on the metabolism of ifications for clinical use. steroid hormones.48 Only a small fraction of the total concentration of unconjugated steroid hormones exists in free form in the C y t o g e n e t ic M e t h o d s blood. Recent developments in under­ Analysis of H-Y antigen has taken on standing the properties of sex hormone special importance with the recognition binding globulin (SHBG) have intro­ that this may be the key factor in gonadal duced a new dimension to the under­ sex differentiation.61 Serologic methods standing of the activity of sex hormones.2 using sperm cytotoxicity26 and mixed Sex hormone binding globulin binds to hemadsorption-hybrid antibody tests40 both testosterone and estradiol. This ap­ are available in several reference labora- parently represents an important mecha­ 284 GONDOS nism for regulating and maintaining sex trol the entry of ovarian germ cells into differentiation.11 Disturbance of this meiosis and the prevention of onset of mechanism may lead to abnormalities of meiosis in the fetal testis.9 The precise sex differentiation. manner of action and characterization of A key role for gonadotropin-releasing these substances remain to be deter­ hormone (GnRH), also known as lutein­ mined, but it was recently reported that izing hormone-releasing hormone (LHRH) the meiosis-inducing substance appears and luteinizing releasing factor (LRF), in to be a steroid.1 Further work in this area regulating pituitary gonadotropin secre­ may provide more specific information on tion has been recognized for a number of the pathogenesis of certain disorders of years.4,30 Radioimmunoassay techniques germ cell differentiation. are available for measuring GnRH activity in the early developmental period.13 Mea­ surement of this hypothalamic hormone is H istopathologic M e t h o d s now considered an essential part of the The immunoperoxidase technique has laboratory evaluation in certain clinical found wide application in surgical pathol­ disorders, using both direct measurements ogy in the past several years. It is now and provocative studies.54 possible to identify specific cell products Bioassays for gonadotropin activity of various types in paraffin-embedded tis­ have been in use in the research labora­ sue. Among the substances that can be tory and may find clinical application. As detected in ovarian and testicular tissue, indicated previously, studies in children particularly germ cell neoplasms, are have shown considerable variation in val­ hCG and alphafetoprotein.41 These deter­ ues obtained by radioimmunoassay and minations enhance diagnostic accuracy bioassay. An assay for LH based on stimu­ and in some cases are needed to establish lation of testosterone production by rat the correct diagnosis as to tumor type or Leydig cell cultures is considered an ac­ types present. In addition, immunoper­ curate indicator of LH activity.15 Simi­ oxidase methods for measuring estrogen larly, the effect of FSH in stimulating receptors have begun to be employed34 androgen binding protein production by and may find clinical application. rat Sertoli cells57 provides a reliable assay Freeze-fracture studies have been for FSH activity using rat Sertoli cell cul­ found to be of particular value in the defi­ tures.21,43 These procedures are much nition of the blood-testis barrier. Occlu­ more detailed and time-consuming than sive Sertoli cell junctions regulating pas­ radioimmunoassay (RIA), but the fact that sage of materials from the circulation into the more easily performed RIA proce­ the testis are clearly identified by this dures may not truly reflect biological ac­ technique. Possible clinical applications tivity should be recognized. are suggested by the observation that in The anti-Mullerian hormone (AMH) germ cell deficient individuals abnormal­ has now been studied in a number of spe­ ities in blood-testis barrier formation cies using a bioassay in which regression occur.10,12 of fetal Mullerian ducts is assessed. Re­ cently, an antibody against AMH has been Summary produced, opening up the possibility for development of a radioimmunoassay The clinical laboratory has a key role in procedure.59 the diagnosis of disorders of gonadal de­ Studies on the regulation of meiosis in velopment. These conditions are associ­ the developing ovary and testis have sug­ ated with specific genetic, chromosomal, gested that a meiosis-inducing substance biochemical, endocrine, and histologic and a meiosis-preventing substance con­ abnormalities which can be identified by ABNORMALITIES IN GONADAL DEVELOPMENT 285 appropriate laboratory procedures. Be­ rier in human germinal aplasia. Anat. Rec. 200:293-297, 1981. cause of the complex activity of the go­ 11. C h a u ssa in , J. L., Br ija n i, A., G e o r g e s , P., nads in germ cell production and hor­ Ro g e r , M., D o n n a d ie u , M., and Job, C.: Vari­ monal function, clinical manifestations ations of serum testosterone estradiol binding globulin (TeBG) binding capacity in infants may be varied and present difficult prob­ during the first year of life. Acta Paediatr. lems in differential diagnosis. Under­ Scand. 67:649-653, 1978. standing of the pathogenesis of the differ­ 12. C h e m e s , H. E., D ym , M., F a w c e t t , D. W., Ja v a d po u r , N., and Sh e r in s , R. J.: Patho­ ent disorders and the proper application physiological observations of Sertoli cells in pa­ of laboratory tests will aid considerably in tients with germinal aplasia or severe germ cell arriving at the correct diagnosis. The depletion. Ultrastructural findings and hor­ mone levels. Biol. Reprod. 27:108-123, 1977. methods available include a wide range of 13. C l e m e n t s , J. A., Re y e s , F. I., Win t e r , J. S. D., cytogenetic, hormonal and histopatho­ and FAIMAN, C.: Ontogenesis of gonado­ logic procedures. Additional newer tests trophin-releasing hormone in the human fetal hypothalamus. Proc. Soc. Exp. Biol. Med. which have undergone increasing clinical 163:437-444, 1980. use in recent years and other procedures 14. COULAM, C. B.: Testicular regression syn­ which are still under investigation for pos­ drome. Obstet. Gynec. 53:44-49, 1979. 15. D u f a u , M. L., Be it in s , I., M cAr t h u r , J., and sible clinical application offer further pos­ CATT, K. J.: Bioassay of serum LH concentra­ sibilities for evaluating and understand­ tions in normal and LHRH-stimulated human ing this complex group of disorders. subjects. The Testis in Normal and Infertile Men. Troen, P. and Nankin, H. R., eds. New York, Raven Press, 1977, pp. 309-325. References 16. 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