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A marsupial has a short gestation period, typically shorter than placental. For more information on how these estimates were ascertained, see Wikipedia's articles on gestational age. The gestation figures given here are shown in days. They represent average values and should only be considered as approximations.
A mare may be in heat for 4 to 10 days, followed by approximately 14 days in diestrus. Thus, a cycle may be short, totaling approximately 3 weeks. [21] Horses mate in spring and summer; autumn is a transition time, and anestrus occurs during winter.
The duration of this period varies between species. For most species, the amount a fetus grows before birth determines the length of the gestation period. Smaller species normally have a shorter gestation period than larger animals. [2] For example, a cat's gestation normally takes 58–65 days while an elephant's takes nearly 2 years (21 ...
Hippomanes first appears in pregnant horses and zebras ca. 85 days from conception, earlier there being small white flecks of tissue debris instead. [1] The changes in hippomanes color correspond to changes in color of allantoic fluid. [1] They are often surrounded by shed cells.
Odd-toed ungulates are characterized by a long gestation period and a small litter size, usually delivering a single young. The gestation period is 330–500 days, being longest in rhinos. Newborn perissodactyls are precocial , meaning offspring are born already quite independent: for example, [ 17 ] young horses can begin to follow the mother ...
The mean pregnancy length has been estimated to be 283.4 days of gestational age as timed from the first day of the last menstrual period and 280.6 days when retrospectively estimated by obstetric ultrasound measurement of the fetal biparietal diameter (BPD) in the second trimester. [12]
Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). [1] It is typical for mammals , but also occurs for some non-mammals.
Gestational age: 6 weeks and 0 days until 6 weeks and 6 days old. 43–49 days from last menstruation. Embryonic age: Week nr 5. 4 weeks old. 29–35 days from fertilization. The embryo measures 8 mm (0.31 in) in length and weighs about 1 gram. [4] Optic vesicles and optic cups form the start of the developing eye. Nasal pits form.