Among them, epidural lipomatosis usually occurs in obese people, patients with a history of corticosteroid use, and those with an endocrinopathy. The Kovalevsky or neurenteric canal is defined as a canal connecting the neural tube and archenteron
in the embryo, resulting from a persisting abnormal communication between the notochord and yolk sac and the amnion during an early stage of embryonic development.
Invagination of the archenteron
is apparent by 46 h PF (Fig.
, gone the way, element: elementum, from LMV, first three
ENTEROCOELE the body cavity formed from an outpocketing of the archenteron
(a primitive digestive cavity), especially typical of echinoderms and chordates [RHD].
These cells then started to darken, losing their transparency (Figure 4A, B), and became located along the inner surface of the body wall; in contrast, cells in normal larvae retained their transparency and were located near the primary gut (archenteron
), moving later through the blastocele to the animal pole (Figure 4C, F).
Some features of early embryos (the blastocoel, the archenteron
of the gastrula) could be seen in specimens pressed gently between a glass slide and coverslip.
Three of the sampled embryos were late gastrulae, with an archenteron
filled with granular material, but not forming coeloms (data not shown).
Embryos from which micromeres have been removed have delayed initiation of gastrulation and a slower rate of archenteron
elongation compared to embryos with micromeres (Ishizuka et al., 2001).
The resulting blastopore started as a wide pit, subsequently deepening into the archenteron
During the initial stages of digestive organ development, the archenteron
of mouth-forming larvae (36 h) had no TRITC-phalloidin-positive fibrous structures (Fig.
The invaginated archenteron
retains a narrow but definite lumen.
Haeckel (1874) suggested that the eumetazoan ancestor was a gastraea with ectoderm, endoderm, and archenteron
with blastopore, essentially having the same structure as that of larval and adult cnidarians and of ontogenetic stages of many bilaterians.