Presentation 16: Reproductive System

Question 1

Overview of Reproductive system (composition, development, some diversity)

Answer 1

• 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)

Question 2

Gonads

Answer 2

Form gametes
Female = ovaries
Male = Testes

Question 3

Ovary composition

Answer 3

Made up of outer cortex (that contains follicles) and inner medulla (w/ neurovascular structures)
- connects to rest of reproductive system via the hilium

Question 4

Ovary cortex

Answer 4

Outer layer that contans ovarian follicles and oocytes and eventually corpus luteum (after ovulation)

Question 5

Ovary Medulla

Answer 5

Inner vascular layer that irrigates the ovary

Question 6

Hilium

Answer 6

part of the ovary that connects to the rest of the reproductive system (w/ blood vessels and nerves)

Question 7

Germinal epithelium

Answer 7

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

Question 8

Components of the Ovary

Answer 8

Germinal epithelium (outer layer)
- primordial germ cells

Cortex
- primary follicles -> follicular cells

Question 9

Layers of Follicular cells

Answer 9

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)

Question 10

What is an adult mammalian follicular cell called?

Answer 10

Graffian follicle (all 4 layers plus antrum)

Question 11

Follicular cells

Answer 11

Primary follicle = develops when primordial germ cells migrate into the cortex

Follicular cells
- support and nourish egg
-secrete estrogens in mammals

Question 12

Describe the process of ovulation and general diversity

Answer 12

1. Wall of follicle ruptures and empties ova out into coelomic cavity
2. 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.

Question 13

Testes - function and general diversity

Answer 13

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

Question 14

Sperm Development

Answer 14

SPERMATOGENESIS (diploid to haploid)
- spermatogonia (diploid)
- spermatocytes (diploid)
- spermatids (haploid)

SPERMIOGENESIS (elongation)
- spermatozoans (sperm cells w/ the tail)

Question 15

What types of cells is sperm in contact with?

Answer 15

Sertoli cells (provide nutrients)

Question 16

Seminiferous tubules are in contact with what type of cell?

Answer 16

Interstitial cells (Leydig cells) - produce testosterone (and other androgens)
reside between tubules/ampullae

Question 17

What surrounds the testes?

Answer 17

Tunica albuginea (fibrous capsule)

Question 18

Male genital duct anatomy and diversity

Answer 18

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

Question 19

Female genital duct

Answer 19

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

Question 20

Female genital duct diversity

Answer 20

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

Question 21

cropodeum

Answer 21

partition of the cloaca in monotremata (opening of the digestive tube)

Question 22

Urogenital sinus

Answer 22

partition of the cloaca in monotremata
(urinary and genital tubes)

Question 23

Oviductal wall layers

Answer 23

Outer wall = connective tissue (serosa)
Middle wall = muscular (myometrium)
Inner wall = mucosal vascular layer (endometrium)

Question 24

What is the size of uterus dependent on?

Answer 24

Degree of fusion of 2 oviducts
- Duplex uterus = little fusion
- bicornuate uterus = more fusion
- simplex uterus = most fusion

Question 25

What are the different copulatory organs?

Answer 25

-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)