(A) ventral (upper) view; (B) typical ornamentation of the outer chorionic reticulum showing two types of tubercles; (C) anterior region of the egg showing micropylar apparatus, formed by a micropilar disc with a well evidenced frame; (D) anterior pole of egg, with micropyle
. Mi, micropyle
; MiC, micropylar collar; MiD, micropylar disc; OCT, outer chorionic tubercle.
The acrosome is a structure absent in fish sperm, being compensated by the micropyle
, a hole in the oocyte chorium where the sperm cell penetrates (GANECO; NAKAGHI, 2003).
Normally the three cells nearest the micropyle
degenerate, leaving only one functional megaspore to develop into the megagametophyte.
Ova are typical of Coeliades and Pyrrhiades spp., almost hemispherical, 1.3mm ([+ or -] 0.03, n=8) diameter and 0.9 mm ([+ or -] 0.00, n=3) height, with 23-27 (mean 24.8 [+ or -] 1.4, n=9) fine ribs from the base to short of the micropyle
, leaving a smooth area around the micropyle
of about 0.7mm diameter .
In coccidia, a pore in the cyst wall closed by a plug of material which is more easily dissolved that the cyst wall; this is where structures formed in the cyst emerge.
A pollen tube begins to grow from a pore in the pollen and a tube nucleus and two sperm nuclei travel along the tube as it grows until it reaches the micropyle
, the opening into the ovule cavity.
Egg architecture of Naucoridae (Heteroptera): internal and external structure of the chorion and micropyle
In teleosts, the only common aspect is the absence of an acrosome, which has been related to the presence of a micropyle
in the egg (Riehl, 1997).
Following germination, inhibition of pollen growth can occur at any time before entering the micropyle
at the base of the ovary and the subsequent fertilization of the egg cell and central cell.
General egg sculpture disappears in the side where micropyle
takes place (Fig.
Sperm enters the egg through the micropyle
, a small opening in the chorion.
57) oblong, bearing conspicuous micropyle
at narrow end, opposite end is papillose; seed coat thick, woody, comprising nearly 20--25% of the diameter of the seed; empty individuals are dark brown to black in color, some specimens are reddish in color due to the reflectance of white endosperm within the seed; examination of endosperm from seeds shows cells intact; embryo present (Fig.