| −4 |
|
|
|
|
Scrotum and mammary primordia |
| 0 |
Birth weight ~ 400 mg |
Neocortex of brain equivalent to 25-d sheep fetus or 12-d rat fetus |
|
|
|
| 2 |
|
|
|
|
Testis cords develop |
| 4 |
|
First axons from retinal ganglion cell layer cross to opposite side of brain via optic chiasm |
|
|
|
| 5-6 |
|
Initial appearance of cortical plate |
|
|
Pouch primordia |
| 8 |
|
|
|
|
Ovarian differentiation starts; Wolffian duct regression |
| 10 |
|
|
|
|
Mullerian duct regression |
| 10-15 |
|
Cortical plate complete throughout telencephalon |
|
Early immune responses start |
|
| 25 |
|
|
|
|
Female germ cells start entry into meiosis |
| 30 |
|
|
Thyroxine (T4) is at adult concentrations, triiodothyronine (T3) is much lower
|
|
Prostate development starts |
| 40-60 |
|
|
|
|
Phallus becomes sexually dimorphic |
| 50 |
|
|
|
|
Germ cell numbers peak in female; most are in meiosis |
| 60 |
|
|
|
|
Testicular descent complete |
| 70 |
|
Mature pattern of eye innervation appears. Completion of six layers of adult cerebral cortex |
|
|
|
| 100 |
Voluntarily releases teat |
|
|
|
|
| 120 |
|
|
Four- to fivefold increase in T4 concentrations
|
|
|
| 120-150 |
|
|
|
Lymph nodes fully developed |
|
| 125 |
|
|
|
|
Milk composition changes from high carbohydrate, low fat and protein to high fat and protein, low carbohydrate |
| 140 |
Eyes open, underfur starts to appear |
|
|
|
|
| 150 |
Capable of some degree of homeothermy |
|
T3 levels increase
|
|
|
| 160 |
Head first out of pouch, able to stand |
|
|
|
|
| 170 |
Starts to nibble grass |
|
|
|
|
| 180 |
Completely homeothermic |
|
Thyroid function complete; T4 levels decline to adult
|
|
|
| 190 |
First out of pouch; able to hop |
|
|
|
|
| 196-252 |
Weaning |
|
|
|
|
| 200 |
Full pelage |
|
|
|
|
| 250 |
Out of pouch permanently |
|
|
|
|
| 280-310 |
|
|
|
|
Females enter puberty |
| 315-350 |
Fully independent: weight 1.6‐2.5.kg |
|
|
|
|
| 570+ |
|
|
|
|
Males enter puberty |
|
| These data are derived from Tyndale-Biscoe and Janssens (1988), Renfree (1994a, 2006), Renfree et al. (1982), and Reynolds
and Saunders (1988).
|
