Female Genital System

Learning Objectives:

At low magnification note the general division of the ovary into an outer cortex containing follicles in various stages of development, and an inner medulla containing blood vessels and dense connective tissue.

 

Durring the Follicular Phase of the ovarian cycle, FSH stimulates the production of follicles in the ovary. See if you can find one follicle in each stage of follicular development, draw or screenshot them in your notes, and describe what distinguishes them from other stages.

Primordial Follicle: Primary oocytes surrounded by single layer of granulosa cells.

Primary Follicle: Early: Follicle cells become more cuboidal; Zona pellucida forms in between oocyte and surrounding follicle cells

Late: Follicle cells form a stratified layer called the stratum granulosum; Follicle cells now called granulosa cells

Connective tissues form theca layers  

Secondary Follicle: Characterized by formation of antrum; cumulus oophorus and corona radiata begin to form

Mature Follicle (Graafian; Tertiary)Large, central antrum. Conspicuous zona pollucida. Primary oocyte is surrounded by a layer of granulosa cells (corona radiata) and rests on a small mound of granulosa cells (cumulus oophorus)

What triggers ovulation?

Surge in Luteinizing hormone. 

Identify and contrast the two primary cellular components of the corpus luteum. What hormone do they produce? What is the function of those hormones in the context of the corpus luteum?

The corpus luteum comprises granulosa lutein cells and theca lutein cells..

Granulosa lutein cells are the larger cells with “frothy” cytoplasm, and are located adjacent to the former antral space. Theca lutein cells are smaller and located at the periphery.

 

The corpus luteum is responsible for the secretion of progesterone during the second half of the ovarian cycle (the "Luteal" phase). Progesterone is responsible for maintaining a uterine environment that can accept and maintain a fertilized egg. When fertilization doesn’t occur, the corpus luteum breaks down, ceases producing those hormones, and causes menstruation.

Iowa Virtual Slidebox: Corpus albicans: 173

What is the corpus albicans?

The corpus albicans is what remains of the corpus luteum after it has stopped producing hormones. It is primarily made of inactive fibroblasts and connective tissue. 

Before you move on, draw or summarize the ovarian cycle, including which phases are under the influence of which hormones. 

Note the convoluted, folded structure of the uterine tube at this location. At high mangnification, observe the two types of epithelial cells in the uterine tube. What are they? What is their function? 

Ciliated cells: Promote movement of secondary oocyte/sperm/embryo

Secretory cells: Secrete a nutritive product for oocyte/sperm/embryo

In which part of the uterine tube does fertilization occur?

The Ampulla

Optional: Iowa Virtual Slidebox: Ovary and fallobian tube: immature (569)

In this slide, you can see the uterine tube at the right of the slide, with a surrounding serosa and suspended by the mesosalpinx.

Iowa Virtual Slidebox: Fallopian tube – isthmus (156)

Note at low magnification the differences in the uterine tube as it approaches the uterus: It becomes narrower and less folded. At higher magnification, you should also observe fewer ciliated cells and More smooth muscle in the muscularis externa.

Compared to other "tracts," The endometrium is a specialized _________________, and the myometrium is a specialized _____________________.

The endometrium is a specialized __mucosa_________________, and the myometrium is a specialized ___muscularis externa__________________.

During the proliferative phase of menstrual cycle, what exactly is proliferating, and under the influence of which hormone?

The Functional zone of the endometrium is proliferating (repairing) under the influence of estrogen.

Compare the proliferative uterus (Slide 21) while you examine the secretory uterus. Capture some images or draw the two structures. Label and describe the differences in the two slides in terms of:

Relative thickness of endometrium: Not very thick in proliferative; thicker in secretory

Shape of glands: Straight in proliferative; coiled in secretory

Staining: Normal in proliferative; lightly acidiophilic because secretion is rich in glycogen

Arterioles: Not readily visible in proliferative; arteries visible and may appear coiled in secretory

During the secretory stage of the menstrual cycle, what is the dominant ovarian structure? Which hormone does it secrete, and what does it do for the endometrium?

The corpus luteum is the dominant ovarian structure during secretory phase of the uterine cycle. It secretes progesterone (primarily), which induces uterine glands to develop and secrete their product for a potential embryo.

During menstruation, which zone(s) of the endometrium is/are lost?

The functional zone is sloughed off during menstruation.

The cervix is a transitional organ and displays different kinds of epithelium. How would you describe the epithelium that is closer to the uterus (i.e., the endocervix), and how would you describe the epithelium closer to the vagina (i.e., the ectocervix)?

The proximal/more internal area of the cervix (endocervix) has a simple columnar epithelium, which transitions to the stratified squamous epithelium characteristic of the ectocervix and of the vagina.

What type of tissue makes up the wall of the cervix?

Smooth muscle

Observe the mucus-secreting epithelial cells comprising the mucosa of the cervix. What purpose might that mucus serve?

Cervical mucus provides lubrication, can impede pathogens from entering the uterus, and can control the transport of sperm (thicker mucus can impede, thinner can promote transport)

Areas of transition between epithelial types are susceptible to neoplastic change. Which area of the female genital tract would you expect to susceptible based on this recurrent observation? Can you think of a screening method that is used for early detection of this cancer?

Pap smears detect neoplastic changes at the squamous-columnar junction of the cervix.

Both the uterine and vaginal epithelium produce glycogen. What role does glycogen play in each of these tissues?

In the vagina, glycogen supports the growth of “good” bacteria. The uterus, glycogen supports embryonic growth.

Note the composition of the walls of the vagina. It has layers of muscularis externa, connective tissue, and is highly vascular.