Female Reproductive histology Flashcards
what are the two co exisiting events during the menstrual cycle?
Ovarian cycle: several ovarian follicles undergo folliculogenesis in preparation for ovulation
Uterine cycle: concurrent cycle, where the endometrium prepares for implantation
Characteristics of the ovary
Lined by ovarian surface epithelium (OSE)
- simple cuboidal epithelium, embryonic source of granulosa cells and stroma cells comprise the growing follicles
- overlying layer of dense connective tissue capsule called the tunica albuginea
Cortex: CT and ovarian follicles
Medulla: CT, intersitial cells, neurovasculature, lymphatics via the hilum
what are the three main cell types found in the ovary?
Mullerian epithelium: epithelial cells originate from the outer epithelial lining
Germ cells: precursor cells of gametes
Sex cord stromal cells: derived from the stromal component of the ovary (granulosa cells, thecal cells, and fibrocytes)
Characteristics of a follicle?
located in the cortical stroma
contain a single oocyte
Follicular/granulosa cells surround the oocyte to support its growth
early stages of oogenesis occur during fetal life
Ocytes present at birth but remain arrested in meiosis I
what are the three phases of folliculogenesis?
Follicular stage
Ovulatory stage
Luteal phase
what is the difference between a primary oocyte and a secondary oocyte?
Primary oocyte: cells that begun 1st meiotic division and are arrested at prophase I
Secondary oocytes: cells tjat complete 1st meiotic division with LH stimulation and enter meiosis II but arrest at metaphase II
what makes up the zona pellucida? and the ovarian stromal cells
coat of glycoproteins that encases the primary oocyte, involved with sperm recognition
Ovarian stromal cells differentiate and form outer coverings that surround the follicle
- Theca interna: steroid producing
- Theca externa: fibroblasts and smooth muscle
Characteristics of the primordial follicles
numerous throughout the cortex
about 25 um in diameter and surrounded by simple squamous layer of folicular/pregranulosa cells
characteristics of the primary follicles
Primordial follicles become primary follicles when single layer of squamous granulosa cells turn to simple cuboidal layer of granulosa cells
basal lamina separates the granulosa cells from the stroma of the ovary
Zona pellucida will begin to assemble, separates primary oocyte from granulosa cells
Characteristics of a late primary follicle
Follicuar cells continue to proliferate
forming a stratified cuboidal follicular epithelium made of granulosa cells
-these cells will communicate via gap junctions
Follicle is still avascular and surrounded by a basement membrane
characteristics of a Secondary follicle
Small spaces appear between the granulosa layers due to cells secreting follicular fluid
- fluid accumulates, the spaces enlarge, and gradually coalesce
- granulosa cells reorganize themselves around a larger cavity, the antrum
What makes up the Theca?
Stromal cells proliferate into a stratified cuboidal epithelium called the theca
Theca interna: vascularixed cell layer adjacent to the basal lamina supporting granulosa that produces androstenedione that is converted to estradiol
theca interna: fibrous cellular layer that is continuous with ovarian stroma
characteristics of a mature Follicle and what happens to the granulosa cells?
also called a Graffian follicle:
- Antrum accumulates more fluid that reaches a size of 2cm
- get thick thecal cells
- bulges at the surface of the ovary that is visible with ultrasound
Granulosa cells will thin out and become segregated by fluid:
- Mural granulosa cells: line follicular wall, actively synthesized and secret estrogen and produce follicular fluid
- Cumulus oophorus: anchor primary oocyte to follicle, and makes a nutrient delivery channel
- Corona radiata: granulosa cells acnchor the zona pellucida
What happens in follicular atrsia?
During a typical menstrual cycle, one follicle becomes the dominant follicle and other primary and antral follicles undergo atresia due to failure of a follicle to ovulate
Apoptosis is the mechanism:
-ensures regression of the follicle with out an causing an immune response
the follicular atresia presents as a glassy membrane due to its thick folded basement membrane material
Ovulatory phase of the Follicle and what does LH cause?
Mature preovulatory follicle protrudes from ovarian surface forming a stigma on the ovary
Proteolytic activity of theca externa and tunica albuginea causes rupture and the follicle enters the uterine tube
LH surge causes the primary oocyte to complete meiosis I making it a secondary oocyte arrested in metaphase II
-oocyte undergoes ovualation and enters oviduct
Mural granulosa cells and the theca interna repair the ovarian surface epithelium (OSE) following the follicle rupture