Felis catus, domestic cat at GeoChemBio: life cycle, developmental stages, embryology

Felis catus, cat development

unfertilized egg Unfertilized mature eggs are usually not released from the ovaries until mating. Read about cat reproductive cycle (mating, estrous cycle).
Prenatal Gestation period lasts from 53-67 (about 9 weeks) ranging from less than 54 to more than 74 days. There are very little data on development of cat embryo in vivo. The following are data from two studies (see Cat main page for references).
- embryo
  - Pre-implantation embryo
    - fertilized egg Ovulation and fertilization occurs in about
      24 - 30 hours after mating. In one study
      natural multiple mating resulted in 73.1%
      fertility in cats (38 of 52). The remaining
      non-fertile cats had either ovulatory or
      fertilization failure. Fertilized egg is
      located in the oviduct. The following time
      intervals are given in hours after first
      copulation (because exact moment when
      fertilization occurs is almost impossible
      to determine).
    - Cleavage Cleavage starts in the oviduct.
      - 2-8 cell embryo In 64 hours after first copulation.
      - 8-16 cell embryo In 76-100 hours after copulation.
    - Morula An early embryo that is a compact mass
      of about 16 cells (blastomeres), which
      differentiated into two types of cells,
      outer cells and inner cells. Morulae and
      compact morulae appear in about 124
      hours post copulation in cats. They are
      still in the oviduct.
      - Compact morula By 148 hour post copulation most
        morulae are compacted and migrated
        into uterus.
  - Blastocyst A preimplantation mammalian embryo that develops from a 32-cell stage into a fluid-filled hollow ball of over a hundred cells. A blastocyst has two distinctive tissues. The outer layer of trophoblasts gives rise to extra-embryonic tissues. The inner cell mass gives rise to the embryonic disc and eventual embryo proper. First blastocysts were found in 148 (~6 days) hours after copulation. The blastocysts undergo intrauterine migration and become equally spaced in the uterus. After this they undergo triphasic implantation (which involves apposition, adhesion, and intrusion).
- Post-implantation
  embryo By 480 hours (20 days) after copulation all normal embryos are implanted and development of fetal membranes and organogenesis had began.
- Fetus At day 53 of pregnancy in the cat, the fetus is almost completely developed inside the amnion (the innermost membranous sac that surrounds and protects the developing embryo which is bathed in the amniotic fluid), which is totally enveloped by allantois (an extra-embryonic membranous sac derived from the yolk sac; it lies between two other extra-embryonic membranes, the amnion and the chorion; the allantois serves to store urinary wastes and mediate exchange of gas and nutrients for the developing embryo).
Post natal
- Neonate Parturition lasts from 2 to 6 hours in majority of cats. Litter size varies from 1 to as much as 13 kittens with average of about 3-5 kittens. Kittens are born with underdeveloped brains and sensory organs: eyes and external auditory canals are closed; mean weight is about 70-110 grams ranging from 30 and up to 170 depending on the breed. Diet is entierly milk. Neonatal period lasts approximately 3-4 days after birth.
- Developing cat
  - Sensory development:
    visual and auditory Eyes usually start opening gradually and symmetrically at about 6-10 days of age; palpebral and blink reflex appear shortly after birth (blink response is getting dulled with age and may be absent by 15-43 days of age especially if the cat is fully awakened). By about 8-17 days of age both eyes are completely open; opening of auditory canals occurs at 4-17 days of age; at this time first startle responses on sharp noises are observed. By end of the first week weight of healthy kitten is nearly doubles.
  - Locomotor development and weaning
    - Uncoordinated
      walking and learning
      to lap (milk, water) At about 3 weeks of age.
    - Starting to play
      and weaning to
      solid food. At about 4 to 7 weeks of age.
- Juvenile Relatively independent and actively growing animal until age of sexual maturity (6-12 months). Independence is achieved at about 10 to 12 weeks of age. About this time, social kittens become more solitary. Plays with peers continue but take on more aggressive character. At about 14 weeks of age social play is almost completely replaced with object play.
- Adult After attainment of sexual maturity. Age of first estrus in female cats ranges from 180 days to 560 days and may depend on date of the birth. On average male and female kittens reach puberty at about 1 year of age. Well-cared for animals can live for 16 years and more.