Verts 10.2 - Reproductive system

Urogenital system

- includes the urinary/excretory systems

- Includes the genital/reproductive systems

- often includes the development of the adrenal glands

Intermediate mesoderm

the urogenital system is derived from the ____ ____ during folding this mesenchyme pulled ventrally

urogenital ridge

At closure of the body wall tissue forms a ___ ___ along the dorsal body wall

Two components = Nephrogenic cord & Gonadal ridge

- Extends from the presumptive cervial somites to the cloaca

Gonadal ridge

There is a thickening of the tissue near the ____ _____

gonadal chords

epithelial cells proliferate and form ___ ____

- subdivided to cortex and medulla

primordial germ cells

the ________ ______ ______ migrate into indeterminate gonads from yolk sac (populate the cords )

Sex hormones

____ ____ determine where the primordial germ cells stop

cortex

females germ cells stop in the _____

medulla

males germ cells stop in the ______

Gonads

______ remain internal except in mammals

Sex Determination

- Female is usually the default

- Male phenotype requires instruction (Ex: Y-chromosomes in mammals)

- Testes = Determining factors

Testes

the determining factors in sex determination

- under this influence the gonadal chords differentiate to the Seminiferous tubules

testosterone

differentiated testes make _____ = responsible for male secondary sexual characteristics

Temperature dependent sex determination

occurs when the sex of an individual is determined by the temperature at which eggs develop

- European pond turtle = high temp --> females

- N. american map turtle = extremes --> females

- agama agama = cold --> females

ovaries

female gonads that are protected by a covering (thin / fibrous)

germ cells

are surrounded by a supportive layer of cells (follicle)

(female gonads)

oovum

as an _____ matures during a cycle the area around it expands

(female gonads)

oviduct

when the mature oovum is released it is picked up by the ______

- transmitted out for external fertilization

- fertilized internally

Cell membrane

- Encloses the nucleus and the cytoplasm

- Specialized proteins for sperm fusion and ion flow during fertilization

(Egg structure)

Fibrous mat

- Surrounds the cell membrane

- Attached to the cell membrane

- Specialized for species recognition during fertilization

(Egg structure)

vitelline envelope

another name for the fibrous mat in external fertilizers

Cortex

- Granules lie just below plasma membrane

- Analogous to the acrosome of sperm

- Contains enzymes/proteins used to PREVENT POLYSPERMY

(Egg structure)

Jelly

- Many species in oocytes have an external _____ layer = external fertilizers

- used for either species-specific sperm attraction and/or activation

Male gonads

- ovid structures

- thousands of Seminiferous tublues

- transmitted to a ductal system for release

seminiferous tubules

- sperm manufacture

- sperm collection

(male gonads)

seminiferous, basal, meiosis

male gonads

- orientation within the _____ standard

- _____ layers have stem cells = proliferative

- Complete _____ as they move towards the LUMEN

Male adaptations

- non-amniotic species use CYSTS or FOLLICLES to mature sperm

- All the sperm in the follicle mature at the same TIME/RATE

- CLONAL MATURATION

Sperm

as the ____ develop in the testes most of the organelles and cytoplasm is lost --> only left with what is needed as very specialized structures

Head, condensed, vesicle

together the nucleus and the acrosome make the _____ of the sperm

- Haploid nucleus becomes very _________

- Acrosome a modified secretory _______

Flagellum

Sperm tail has a ____ that allows for propulsion

mitochondria

energy for sperm flagellum propulsion comes from the _____ located in the midpiece

Mesonephric, Paramesonephric

Males and females start with 2 ductal systems

= _____ & _______ duct

Mesonephric (archinephric) ducts

- aka Wolffian duct

- from the developing urinary system

Paramesonephric duct

- Develops lateral to the nephric system

- aka Mullerian duct

males, females

Archinephric ducts remain in the _____ but this system degenerates in ______

epididymis

the proximal region becomes the ______

(In the male archinephric ducts)

vas deferens, ejaculatory duct

the distal region becomes the ______ ____ and _____ ____

(In the male archinephric ducts)

testosterone, wollfian

Male ducts persist because the testes makes ____ --> promotes the differentiation of the ______ system

Mullerian Inhibiting Substance (MIS)

Male ducts also make ____ _____ _____ which blocks the formation of the mullerian duct

MIS, paramesonephric, funnel, species specific

Female Genital Duct systems:

- Develop in the absence of _____

- __________ ducts = lateral to mesonephric ducts and gonads

- cranial ends are ____ shaped and open to the abdominal cavity (FIMBRIAE of fallopian tubes)

- _____ _______ differentiation along length (shell glands/fused uterovaginal regions)

Lamprey Reproduction Anatomy

- Orientation of the gonads in less derived vertebrates (back wall of coelom)

- Females 200,000 follicles develop at once

- GAMETES RELEASED INTO BODY CAVITY (enter the kidney ductal sys --> released from cloaca)

Sharks

____ (elasmobranchs) often only one ovary fully develops

Mullerian

Sharks have differentiation of the _____ duct into 4 regions

- funnel

- shell gland

- Istmus

- uterus

Shell gland

(nidamental gland)

- Not an amniotic shell

- Oviviparous birthing method = gestation in shell, hatch from shell, released live from uterus

Teleost variation in females

- Some lack very complex ductal systems (Salmonids)

- Oocytes released, in large numbers, into body cavity (Picked up by short ducts)

- Other teleosts have the Mullerian ducts regress completely (New oviduct are formed from PERITONEAL FOLDS)

Amphibians

______ have paired ovaries

- standard oviduct system

- oocytes are released for external fertilization

amniotes

In _____ the mullerian system differentiates

- muscular walls for transmission of fertilized ova

- mucus membrane for support

Ovo-viviparous

hatched from egg internally and expelled live

Oviparous

hatched from live egg incubated outside mother (chickens are an example )

Viviparous

no egg shell, expelled live from mother

(partial midline fusion of tubes for implantation and placental dev) ??

Lamprey

In _____ there are NO DUCTAL SYSTEMS --> sperm empty into coelom and exit a penis-like structure

Male Sharks

Some species of _____ ______ have adapted the Mullerian ducts to move sperm (archinephric ducts are ONLY for urine)

Teleosts

In _____ the male ductal system doesn't develop from Archinephric ducts (Separate set up = PERITONEAL TISSUES)

kidneys, ducts

•As the archinephric _________ become less important for urine production the ________ are repurposed

amphibians

some ____ use the archinephric ducts for both urine and sperm

Male amniotes

use the archinephric ducts EXCLUSIVELY for Sperm

metanephric

in male amniotes urine is transmitted by the _____ duct (mot mesonephric)

scrotal sacs

mammals often reposition the testes in _____ _____

- cooling mechanism

- 8* C difference

Internal testes

descend completely during mating season

External testes

_____ (pre or post penile)

- Descend during development

- Move through the abdominal wall

mammals

some ____ lack a scrotum (aquatic)

Aquatic mammals

- Hydrodynamics of swimming

- Testes are kept cool via counter current vascular network