ANFS345: Reproductive System

Factors for Egg and Sperm to Meet

environment cues, change of location, reproductive organ development, acquisition of resources, attraction between male and female, spawning or copulation

Factors for Successful Offspring

development of zygote, provisioning of offspring, early epigenetic tagging, diversion of parental time, confrontation of environmental stress, evasion of predators

Mammalian Sex Chromosomes

xx female, xy male

Mammalian Sex Determination

x or y chromosomes from father

Bird Sex Chromosomes

zz male, zw female

Bird Sex Determination

z or w chromosome from mother

Ant Sex Determination

fertilized eggs female, non fertilized male

Painted Turtle Sex Determination

temperature at critical period, hot female, cool male

Clownfish Sex Determination

switch sex in dominance hierarchy

Seasonality of Reproduction

reproductive period can range from 1-2 months in the far north to all year in the south in some rats

Silkworm Moth Reproductive Seasonality

eggs hatch and mature in spring to summer, eggs enter dipause to survive winter, once the cold ends they can hatch

Antarctic Fur Seal Reproductive Seasonality

conception in early summer, dipause with delayed implantation until autumn, placental development for 250 days, timing for summer babies

External Genitalia Development

differentiation begins after 4 weeks, hormone levels allow for proper development

Total Ovulation Events

300-400

Cervix

sensory for muscle contractions, important in birth and copulation

Uterus

site of pregnancy and embryo implantation

Ovary

site of egg storage and ovulation, 2 in mammals, 1 in birds

Primordial Follicle

follicles female is born with, thousands

Primary Follicle

immature ovum that begins to grow and develop

Secondary Follicle

one selected follicle to mature for ovulation

Secondary Follicle Accessory Tissues

theca cells, granulosa cells, antrum

Corpus Luteum

forms from ruptured follicle

Corpus Luteum Function

produces hormones to sustain pregnancy

Hormones That Peak at Ovulation

FSH, LH, estrogen

Inhibin

peaks just after estrogen peaks, controls estrogen levels

Endometrium Phases

proliferative phase, secretory phase, menstrual phase

Estrus Timing

ovulation coincides with estrus in most animals

Animals That Get Periods

monkeys, apes, humans, elephant shrews, bats

Pregnancy Health Concerns

fatigue, high blood pressure, diabetes, pre-eclampsia

Why Have Periods

womb sheds endometrium in protective process, flushes out dead or nonviable oocytes

Ovulation Related Hormones

GnRH, FSH, LH, androgens, estrogen

Hypothalamus Releasing GnRH Triggers

GnRH acts on anterior pituitary gland

GnRH to Anterior Pituitary Triggers

anterior pituitary secreted LH and FSH

LH Secretion Triggers

stimulation of theca cells

Stimulation of Theca Cells Triggers

production of androgens (male hormones)

Androgen Production Triggers

movement into granulosa cells

Androgens in Granulosa Cells Triggers

aromatase action on androgens

Aromatase Action Triggers

androgens into estrogen

Estrogen Production Triggers

granulosa cell proliferation

FSH Secretion Triggers

aromatase to act in granulosa cells

Superficial to Deep Oocyte Layers Pre-Ovulation

theca cells, granulosa cells, zona pellucida, oocyte

LH Surge

1-2 hours post copulation, peak corresponds with ovulation

Copulation Triggers

sensory neuron impulses in cervix

Sensory Impulses from Cervix Triggers

production of norepinephrine in brainstem

Norepinephrine in Brainstem Triggers

GnRH production

Testes Function

sperm and testosterone function

Sperm Requirments

semen with nutrients, motility

Leydig Cells

produce testosterone in seminiferous tubules

Sperm Head Components

acrosome, nucleus

Sperm Midpiece Components

lots of mitochondria

Sperm Tail

very long, required for motility

Sperm Goal

get male DNA to oocyte to fertilize it

First Testosterone Activity

~11-17 weeks post conception, required for development of male genitalia

Second Testosterone Activity

short peak after birth

Final Testosterone Activity

sharply increases at puberty and levels out during reproductive ages

Puberty Timing

occurs at high nutritional plane, happening earlier than few generations ago

Teste Size Relationship

larger testes found in multi-male mating systems for mammals and primates

Large Teste Ability

more sperm and testosterone production

Superficial to Deep Secondary Oocyte Layer Post-Ovulation

theca cells, granulosa cells, zona pellucida, perivitelline space, oocyte membrane, oocyte cytoplasm

Sperm and Granulosa Cells

enzymes digest theca and granulosa cells

Sperm and Zona Pellucida

binds to species specific receptors, acrosomal reaction releases enzymes

Sperm and Oocyte Membrane

proteins bind together, allow sperm to release contents into cytoplasm

Sperm Binding Protein

lzumol1

Oocyte Binding Protein

juno

Chorionic Gonadotropin Hormone

peaks 40 days post fertilization, measured on pregnancy strips

Pregnancy Hormone Levels

estrogen and progesterone gradually increase, sharply drop off at parturition

Myometrial Contractions Trigger

fetus pushed against cervix

Fetus Cervix Contact Triggers

mechanoreceptors signal to hypothalamus

Mechanoreceptor to Hypothalamus Triggers

oxytocin secretion

Oxytocin Triggers (parturition)

myometrial smooth muscle contractions and prostaglandin production

Prostaglandin Production Triggers

myometrial contractions, positive feedback

Types of Birth Methods

placental, marsupials, monotremes

Placental Births

placenta to uterus to support embryo

Marsupial Births

young birthed to begin secondary development inside pouch

Monotreme Births

soft shelled eggs

Mother Energy Needs

increased during gestation, sharply rises after parturition due to lactation

Lactation Milk Path

alveoli to milk ducts to cistern to teat

Suckling Triggers

mechanosensory stimulation

Mechanosensory Teat Stimulation Triggers

reduced dopamine, increased TRH

Hypothalamus Product Changes Triggers

prolactin and oxytocin secretion

Oxytocin Secretion Triggers (lactation)

myoepithelial cells contract and eject milk

Prolactin Secretion Triggers

secretion of milk into lumen of alveoli