Presentation 16: Reproductive System Flashcards
Overview of Reproductive system (composition, development, some diversity)
- composed of gonads that form gametes
- develop from embryonic mesomere portion called the genital/gonadal ridge
- gonads are usually paired (except in agnathans)
- for vertebrates - female pattern of development (won’t become male unless there are specific hormones)
Gonads
Form gametes
Female = ovaries
Male = Testes
Ovary composition
Made up of outer cortex (that contains follicles) and inner medulla (w/ neurovascular structures)
- connects to rest of reproductive system via the hilium
Ovary cortex
Outer layer that contans ovarian follicles and oocytes and eventually corpus luteum (after ovulation)
Ovary Medulla
Inner vascular layer that irrigates the ovary
Hilium
part of the ovary that connects to the rest of the reproductive system (w/ blood vessels and nerves)
Germinal epithelium
outside layer of ovary, invaded by primordial germ cells that migrate into the cortex and become primary follicles that eventually develop into follicular cells that surround oocytes
Components of the Ovary
Germinal epithelium (outer layer)
- primordial germ cells
Cortex
- primary follicles -> follicular cells
Layers of Follicular cells
4 Layers in all vertebrates, 5 layers in mammals
- Ova/Oocyte (inner egg)
- zona pellucida (non-cellular layer of space between egg and follicular cells)
- Follicular cells = corona radiata in mammals)
- Antrum (fluid filled space btw follicular cells and theca, ONLY IN MAMMALS)
- Theca (layer of cells from medulla that surround follicular cells)
What is an adult mammalian follicular cell called?
Graffian follicle (all 4 layers plus antrum)
Follicular cells
Primary follicle = develops when primordial germ cells migrate into the cortex
Follicular cells
- support and nourish egg
-secrete estrogens in mammals
Describe the process of ovulation and general diversity
- Wall of follicle ruptures and empties ova out into coelomic cavity
- remaining tissue of follicle become corpus luteum (which later becomes part of endocrine system to produce estrogen + progesterone)
Teleosti - ovaries are hollow so ova moves into a coelomic cavity inside ovaries which is connected to outside through a gonaduct.
Testes - function and general diversity
Produces sperm + steroid hormones
Contain cavities where sperm is produced
- Anamniotes = spermatic ampullae (all developing cells are at same stage of development in each cavity)
- Amniotes = seminiferous tubules (have all stages of sperm development
Sperm Development
SPERMATOGENESIS (diploid to haploid)
- spermatogonia (diploid)
- spermatocytes (diploid)
- spermatids (haploid)
SPERMIOGENESIS (elongation)
- spermatozoans (sperm cells w/ the tail)
What types of cells is sperm in contact with?
Sertoli cells (provide nutrients)
Seminiferous tubules are in contact with what type of cell?
Interstitial cells (Leydig cells) - produce testosterone (and other androgens)
reside between tubules/ampullae
What surrounds the testes?
Tunica albuginea (fibrous capsule)
Male genital duct anatomy and diversity
Agnathans: Sperm released into coelomic cavity and emerges into world via genital pores within the body wall
Gnathostomes:
- sperm formed in seminifererous tubules collectes into rete testes then moves through efferent ductules called (vasa efferentia in mammals) to the epididymis and then out the sperm duct (aka ductus deferens)
- derivatives of the mesonephric ducts, it carries both urine and sperm so it is called a urogenital duct
Female genital duct
Agnathans: lack oviduct (egg moves from coelomic cavity out genital pores)
Gnathostomes:
- Second duct alongside mesonephric duct (only functionin in mammals) called the muellerian duct which gives rise to the oviduct. The egg moves from the ovary into the funnel shaped infundibulum and through the ostium into the oviduct, eventually out of the cloaca
Female genital duct diversity
Monotremata (egg laying mammals)
- partition of the cloaca into 2 parts, the cropodeum and the urogenital sinus
Therian mammals
-Oviduct differentiates into oviduct, uterus, and vagina (uterus and vagina meet at cervix)
Marsupials
- oviducts remain separated by the ureters
- forms 2 uteri and 2 vagina
cropodeum
partition of the cloaca in monotremata (opening of the digestive tube)
Urogenital sinus
partition of the cloaca in monotremata
(urinary and genital tubes)
Oviductal wall layers
Outer wall = connective tissue (serosa)
Middle wall = muscular (myometrium)
Inner wall = mucosal vascular layer (endometrium)
What is the size of uterus dependent on?
Degree of fusion of 2 oviducts
- Duplex uterus = little fusion
- bicornuate uterus = more fusion
- simplex uterus = most fusion
What are the different copulatory organs?
-Ovipositor (sac in males for females to directly lay eggs in)
- Gonopodium (fins w/ small groove on top that funnels sperm to females
- Claspers (e.g. sharks)
- Hemipenes (structure that is reflected outside that differs btw species to match up and lock w/ female reproductive organ)
- Phallodeum (similar to hemipenes, inverted structure has species specific ridges to lock up w/ female reproductive organs)
- True penis - in ostriches and mammals (may have bones called baculum)
