Introduction The slides for this lab are located in the “Female Reproductive” folder on the Virtual Microscope. This guide provides you with a description of the slides that you will be examining and a short conceptual framework for studying them.
The female reproductive system consists of internal sex organs and external genital structures. This lab focuses on the histology of the internal sex organs which include the ovaries, uterine tubes, uterus and vagina.
These organs undergo regular cyclic changes from puberty to menopause under the influence of a number of different hormones. It is not the purpose of this laboratory to discuss these pathways but it is important that you do start to make these correlations as you study the physiological regulation of the female reproductive system.
Learning objectives and activities Using the Virtual Slidebox:
A Examine the structures of the ovary and trace the development of follicles from primordial follicle, through ovulation to formation of the corpus albicans.
B Identify the different regions of the uterine tube based upon their histological organization.
C Observe the uterus and determine the structural and functional changes that occur in the endometrium during the menstrual cycle.
D Examine the histological features of the vagina.
E Complete the self-quiz to test your understanding and master your learning Examine the structures of the ovary and trace the development of follicles from primordial follicle, through ovulation to formation of the corpus albicans
Examine Slide 1 and Slide 2 to identify the basic features of the ovary and find examples of follicles at each stage of folliculogenesis.
The ovaries are paired, almond-shaped structures that are attached to the pelvic wall by the suspensory ligament of the ovary (conveys ovarian vessels) and to the uterus by the ovarian ligament. Histologically it is composed of medulla and cortex and contains numerous follicles that are at different stages of maturation depending on the stage of menstrual cycle at the time of fixation and processing. i. General organization
a. Cortex - found in peripheral ovary surrounding medulla Identify cortex in - contains most of the ovarian follicles Slide 1a and Slide 2a - loose irregular CT and scattered smooth muscle fibers - boundary between cortex and medulla is indistinct
b. Medulla - central portion of ovary Identify medulla in - composed of loose irregular CT Slide 1b and Slide 2a - contains a mass of contorted blood vessels and nerves
c. Germinal epithelium Find evidence of the - simple cuboidal epithelium covering the ovary germinal epithelium in - continuous with the mesovarium Slide 1c and 2c
d. Tunica albuginea - a region of dense irregular CT Find the tunica - lies between germinal epithelium and cortex albuginea in Slide 1d and 2d ii. Folliculogenesis
e. Primordial follicles Find examples of - are located in superficial cortex primordial follicles in - are lined with simple squamous follicular cells Slide 1e and Slide 2e - contain a primary oocyte arrested in prophase I meiosis
f. Primary/growing follicles (unilaminar) Find examples of - are often located deeper in the cortex than primordial follicles unilaminar primary - are lined with simple cuboidal-columnar follicular cells follicles in - have developed a zona pellucida Slide 1f and Slide 2f - contain a primary oocyte arrested in prophase I meiosis
g. Primary/growing follicles (multilaminar) - are lined with stratified columnar follicular cells Find examples of - the follicular cells are now called stratum granulosum multilaminar primary - have developed a zona pellucida follicles in - contain a primary oocyte arrested in prophase I meiosis Slide 2g - connective tissue around follicle organizes to form theca folliculi
h. Secondary/antral follicles - are characterized by development of an antrum within the stratum granulosum that is filled with liquor folliculi Find examples of - contain a primary oocyte arrested in prophase I meiosis secondary follicles in - theca folliculi differentiated to form: Slide 1h and 2h i. theca interna: produce androstenedione ii. theca externa: CT and smooth muscle
i. Tertiary/Graafian follicles - are the largest follicles - have a large antrum - on Day 13 of the menstrual cycle the LH surge causes the Find the Graafian primary oocyte in the follicle to resume meiosis follicle and its - this division means the Graafian follicle contains a secondary components in oocyte that is: Slide 1i and 2i i. arrested in metaphase II of meiosis ii. surrounded by cloud of granulosa cells (corona radiata) iii. connected to peripheral granulosa cells by a thin stalk called the cumulus oopherus. j. Atretic follicles - represent the follicles that are lost due to mediated apoptosis of Find example of large stratum granulosum cells and small atretic - are formed durin fetal development and during adulthood follicles in - they may be small (apoptosis of primary and primordial follicles) Slide 1j and 2j - they may be large (apoptosis of a secondary follicle that was not selected to mature to Graafina stage)
Following ovulation of the secondary oocyte and its corona radiata, the structures of the Graafian follicle persist in the ovary temporarily where it acts as an endocrine gland capable of supporting the uterine endometrium in case fertilization and implantation take place. This structure is called the corpus luteum. If pregnancy occurs the corpus luteum grows to occupy a large portion of the ovary under the control of human Chorionic Gonadoptrophin (hCG) and assists with the endocrine support of the pregnancy for. After 6mmths of preganancy or if fertilization does not occur within 14 days of ovulation the corpus luteum degenerates to form a corpus albican ‘scar’
Examine Slide 3 to identify features of the corpus luteum and Slide 4 to see a corpus albican
a. Corpus luteum Examine the corpus - a large, temporary endocrine organ composed of the remnants luteum in of the Graafian follicle after ovulation has occurred. Slide 3a - these remnant structures reorganize to form specialized regions of endocrine cells
b. Granulosa lutein cells - are derived from the stratum granulosum of the Graafian Find the granulosa - form the bulk of the wall lutein cells in - produce progesterone Slide 3b - converts androgens produced by theca lutein cells into estrogen
c. Theca lutein cells - are located peripherally Find the theca lutein - are derived from the theca interna of the Graafian cells in - produce progesterone and androgens Slide 3c - converts androgens produced by theca lutein cells into estrogen
d. Corpus albicans - the CT scar remnant of a degenerated corpus luteum. Find the corpus albicans in Slide 4 Stratified with developing antrum Stratified columnar
Atretic (dying) Secondary Primary follicle Simple cuboidal/columnar follicle follicle Approaching (multilaminar) maturity
Simple squamous Primary follicle (unilaminar)
Primordial Peripheral; large; follicle well developed antrum
Tertiary/mature/ Graafian follicle
Primary Secondary oocyte
Corpus albicans
Ovulated oocyte
Corpus luteum Ruptured follicle Corpus hemorrhagicum Identify the different regions of the uterine tube based upon their histological organization.
The uterine tubes are paired tubes that extend bilaterally from the uterus toward the ovaries. The transport the ovulated secondary oocyte toward the uterus and are the site of fertilization. i. Infundibulum (and fimbrae) The funnel shaped initial segment of the uterine tube that is fringed with fimbrae.
Observe the organization and key features of the infundibulum in Slide 5
a. Fimbrae - extend from the mouth of the infundibulum Identify fimbrae in - sway to assist in acceptance of the ovulated oocyte from the Slide 5a surface of the ovary
b. Mucosa Identify the mucosa in - composed of the epithelium and CT lamina propria Slide 5b
c. Ciliated epithelial cells Find ciliated - a ciliated simple columnar epithelium epithelium in - cilia sway with metachronal rhythm to assist in drawing the Slide 5c oocyte into the uterine tube
d. Muscularis mucosa Identify muscularis - a region of poorly defined smooth muscle mucosa in Slide 5d e. Serosa - a thin layer of connective tissue covered in peritoneum (mesothelium) Identify the serosa in Slide 5e ii. Ampulla The longest segment of the uterine tube also has the most folds in its mucosa surface. It is also the most common site of fertilization.
Observe the organization and key features of the ampulla in Slide 6
a. Mucosa Identify mucosa in - composed of the epithelium and CT lamina propria Slide 6a - is very highly folded in the ampulla
b. Ciliated epithelial cells Find ciliated - a ciliated simple columnar epithelium epithelium in - cilia sway with metachronal rhythm to assist in transport of Slide 6b oocyte through the uterine tube
c. Non-ciliated epithelial cells (Peg cells) - relatively rare cells that lack cilia Find peg cells in - secrete a nutrient rich secretion that nourishes the ova as it Slide 6c waits to be fertilized and is also thought to be involved in capacitation of the spermatozoa - nuclei appear more superficial than surrounding cells
d. Muscularis mucosa Identify muscularis - a region of poorly defined smooth muscle mucosa in Slide 6d e. Serosa - a thin layer of connective tissue covered in peritoneum Identify serosa in (mesothelium) Slide 6e ii. Isthmus The narrow segment of the uterine tube that lies adjacent to but does not pass through the uterine wall.
Observe the organization and key features of the isthmus in Slide 7
a. Mucosa - composed of the epithelium and CT lamina propria Identify mucosa in - has folds but would not be described as ‘highly folded’ Slide 7a
b. Ciliated epithelial cells Find ciliated - a ciliated simple columnar epithelium epithelium in - cilia sway with metachronal rhythm to assist in transport of Slide 7b oocyte through the uterine tube
c. Non-ciliated epithelial cells (Peg cells) - relatively rare cells that lack cilia Find peg cells in - secrete a nutrient rich secretion that nourishes the ova as it Slide 7c waits to be fertilized and is also thought to be involved in capacitation of the spermatozoa - nuclei appear more superficial than surrounding cells
d. Muscularis mucosa Find muscularis - a region of poorly defined smooth muscle mucosa in Slide 7d e. Serosa - a thin layer of connective tissue covered in peritoneum (mesothelium) - not readily observed in the slide provided Observe the uterus and determine the structural and functional changes that occur in the endometrium during the menstrual cycle.
The uterus is a hollow, pear-shaped organ that is continuous with the uterine tubes superiorly and vagina inferiorly. Its wall is composed of an endometrium, myometrium and perimetrium of which the endometrium undergoes significant changes each month to prepare for implantation of an embryo.
Examine Slide 8 to identify the basic features of the uterus in the proliferative phase i. Proliferative/Follicular stage (Days 5-14)
a. Endometrium (mucosa) - is composed of the stratum basale (basal layer) Identify the - is composed of the stratum functionalis (functional layer) endometrium in - contains glands and vessels that are proliferating under the Slide 8a influence of estrogen - is lined by a simple columnar epithelium
b. Stratum basale - sits on the myometrium Identify stratum - undergoes few changes during the cycle basale in - is not shed during menstruation Slide 8b - is the source of regeneration of the stratum functionalis
c. Stratum functionalis - continuous with the stratum basale Identify stratum - in the proliferative phase is characterized by: functionalis and its i. large amounts of growth (therefore mitotic figures) features in ii. developing straight endometrial glands Slide 8c iii. growing spiral arteries
d. Myometrium (muscularis mucosa) Identify myometrium - is formed by four, indistinct, interwoven layers of smooth muscle in - is the thickest part of the uterine wall Slide 8d e. Perimetrium - the outer aspect of the uterine wall (not seen in this slide). Examine Slide 9 to identify the basic features of the uterus in the secretory phase ii. Secretory/Luteal stage (Days 14-28)
a. Endometrium (mucosa) - is composed of the stratum basale (basal layer) Identify the - is composed of the stratum functionalis (functional layer) endometrium in - contains glands and vessels that are proliferating and commence Slide 9a secretion under the influence of progesterone - is lined by a simple columnar epithelium
b. Stratum basale - sits on the myometrium Identify stratum - undergoes few changes during the cycle basale in - is not shed during menstruation Slide 9b - is the source of regeneration of the stratum functionalis
c. Stratum functionalis - continuous with the stratum basale Identify stratum - in the secretory phase is characterized by: functionalis and its i. large, well developed, saw-tooth glands features in ii. secretions in the lumen of the glands Slide 9c iii. well developed spiral arteries
d. Myometrium (muscularis mucosa) Identify myometrium - is formed by four, indistinct, interwoven layers of smooth muscle in - is the thickest part of the uterine wall Slide 9d e. Perimetrium - the outer aspect of the uterine wall (not seen in this slide).
Examine Slide 10 to identify the basic features of the uterus in the menstrual phase iii. Menstrual phase (Days 0-5)
a. Endometrium (mucosa) Identify menstrual - only the stratum functionalis is shown in this slide phase in Slide 10a b. Stratum functionalis - shed from the endometrium due to drop in progesterone triggered by a degenerating corpus luteum Identify stratum - in the menstrual phase is characterized by: functionalis in i. regions of necrosis Slide 10b ii. blood due to necrosis of spiral arteries Examine Slide 11 to identify the basic features of the uterine cervix iv. Cervix
a. Endocervix Identify the - is lined with a mucous secreting uterine (simple columnar) endocervix in epithelium Slide 11a - contains cervical glands
b. Ectocervix Identify the ectocervix - is lined with vaginal epithelium (nk. stratified squamous) in Slide 11b
c. Transformation zone - the junction between endocervix and ectocervix Identify the - it is located just outside the external os transformation zone in Slide 11c d. Cervical stroma - the rest of the wall of the cervix is composed of a dense fibromuscular stroma. Identify cervical - the hormone relaxin, released during parturition, is thought to stroma in assist in the digestion of collagen fibers in the cervix which Slide 11d allows it to dilate to permit passage of the fetus
e. Cervical gland - mucous secreting glands in the cervical mucosa - the consistency of mucus secreted changes depending on the Identify a cervical stage of the menstrual cycle gland in - mucus is less viscous mid-cycle providing a more favorable Slide 11e environment for sperm migration - at other times it is more viscous acting to protect the uterus from entering bacteria
f. Nabothian cysts Identify Nabothian - are commonly observed blocked glands that appear dilated cysts in - they are so common as to be deemed a normal finding Slide 11f Examine the histological features of the vagina.
Examine Slide 12 to identify the major features of the vagina.
The vagina is a fibromuscular sheath that functions as the terminal aspect of the birth canal and the site of copulation. i. Organization
a. Mucosa Identify mucosa in - a thick non-keratinized stratified squamous epithelium Slide 12a - underlying loose irregular CT lamina propria
b. Non-keratinized stratified squamous epithelium Identify non- - epithelial cells store glycogen keratinized stratified - when sloughed glycogen is release and acts as nutrient for squamous epithelium vaginal flora in - bacteria metabloze glycogen and release lactic acid resulting in Slide 12b an acidic, protective pH
c. Muscularis mucosa Identify muscular - thick smooth muscle wall composed mucosa in - inner circular muscle blends with outer longitudinal layer Slide 12c
d. Adventitia - not shown in this slide - dense irregular CT with elastic fibers In addition to all the basic tissues in slides that are relevant to interpreting tissue structure you must be able to identify the following structures and their features
Ovary Uterus Cortex Endometrium Medulla Myometrium Germinal epithelium Stratum functionalis Tunica albuginea Stratum basale Primordial follicle Uterine glands Primary follicle (unilaminar) Spiral arteries Primary follicle (multilaminar) Arcuate arteries Secondary/growing follicle Secretory phase Graafian/tertiary follicle Proliferative phase Stratum granulosum Menstrual phase Zona pellucida Mitotic figure Theca folliculi Uterine cervix Theca interna Ectocervix Theca externa Endocervix Cumulus oophorus Transformation zone Corona radiate Cervical glands Atretic follicle Nabothian cyst Corpus luteum Fibromuscular stroma Theca lutein Granulosa lutein Corpus albicans
Uterine tube Vagina Mucosa Mucosa Muscularis mucosa Muscularis Serosa Non-keratinized stratified Ciliated epithelial cells squamous epithelium Non-ciliated epithelial cell/Peg cells Glycogen Infundibulum Fimbrae Ampulla Isthmus