Friday, January 21, 2011

Fetal Rat Dissection

Class Mammalia
Pregnant Rat Dissection

Mammary glands - produce milk.
Viviparous development - retained within body of female to keep warm.
Nourishment - blood vessels through placenta (allows exchange of nutrients and wastes).


Babies out of the uterus.

Mama rat's eleven babies.

Some info - pregnant, double injected, vacuum packaged -
but  unfortunately not how far along she is!
 Reproduction

 - in the female, the uterus passes to the bladder. Where the horns of the uterus join to the urethra, is the vagina which opens to the exterior through the vaginal opening. On the exterior the anus is anus is ventral to the tail, the vaginal opening is ventral to the anus and the urethral opening is ventral to the vagina. The ovary is found at the anterior end of each uterine horn. The embryos form inside the uterus, along each 'horn'.

- in the male, the testes are located in the scrotum. The epididymis is located around each testis and the vas deferens leads from each testis to the urethra. On either side of the bladder are the prostate glands and seminal vesicles. The urethra goes through the penis, and both the bladder and the testes empty to the outside through the urethra.


Reproductive Organs
Uterus - consists of two tubes (horns), y-shape allows for the growth of multiple embryos.
Ovaries - pea-sized organs.
Oviducts - tightly coilded tubes leading from the ovaries to the horns of the uterus.
Vagina - opens to the exterior through the vaginal opening.
Penis - found in the fur covered prepus (foreskin).
Epididymis - where sperm are stored, highly convoluted tubules.
Vas deferens - carries spern to the urethra.
Testes - where the sperm is produced.

Mama rat's big - she's got babies that were growing inside her.

Many nipples for feeding her many young.

Urethral opening, vaginal opening, anus.

Uterus - each 'bubble' has a fetus inside.

Anterior end of one uterine horn - ovary.

Fetus - out of the embryonic sac.

Nourishment - blood vessels through placenta -
allows exchange of nutrients and wastes.

Horn/y-shaped uterus means room for lots of babies!

A very tiny rat fetus.

Eyes are not developed until after the rat is born.



 

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