11: Repro Behaviors

Purpose of reproductive behaviors

To increase the chances for copulation and pregnancy

When do females exhibit reproductive behaviors

During estrus

Primary behavior associated with estrus

Sexual receptivity

When do males exhibit reproductive behaviors

Any time after puberty

Hormone responsible for embryonic sexual differentiation

E₂ (or the lack of it)

Factors that result in the female hypothalamus being feminized

α-fetoprotein prevents maternal and fetal E₂ from crossing the embryonic blood-brain-barrier, resulting in a feminized hypothalamus

Factors that result in the male hypothalamus being defeminized

α-fetoprotein only binds up E₂ in circulation. In males, T₂ crosses the embryonic blood-brain-barrier and gets aromatized to E₂ inside the brain, defeminizing the hypothalamus

Mechanisms that control reproductive behaviors

Neuroendocrine reflexes and hormone release

Triggers for the reflexes that control repro behavior

Input from all the senses

Type of reflex that drives erection

PS-ANS

Nerves responsible for the erection reflex

Sacral plexus

Hormone that drives all the repro behaviors in males and females

E₂

Where do males get E₂

T₂ from Leydig cells is converted to E₂ (and DHT) in Sertoli cells

Where do females get E₂

Follicles

Specialized organ for the detection of pheromones

Vomeronasal organ

How is erection achieved in species with a musculocavernosus penis

Contraction of the ischiocavernosus muscle blocks venous return, resulting in a build up of blood within the sinuses of the erectile tissue

Signaling pathway that provides the vasodilation for erection

NANC neurons → release of NO

How is erection achieved in species with a fibroelastic penis

Relaxation of the retractor penis muscle

What allows sperm to have proper motility

Coating of seminal plasma proteins

Capacitation of sperm

Removal of the coating proteins from the seminal plasma

Result of capacitation

Hypermotility and unmasked zona pellucida binding sites

Length of sperm viability

Hours to many days

Length of oocyte viability

Several hours