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