Anomalías congénitas / Congenital anomalies

Las anomalías congénitas en conjunto con la restricción del crecimiento intrauterino dan cuenta del 50 a 60 por ciento de la mortalidad fetal. En este artículo se describen las malformaciones congénitas más importantes divididas por sistemas, la mayoría son diagnosticables a través del ultrasonido; sin embargo, hay un grupo de ellas que no son posibles de diagnosticar, otras que se desarrollan tardíamente en el embarazo y finalmente existen casos en que el examen ultrasonográfico puede sugerir una anormalidad inexistente. También se profundiza en la incidencia, etiología y factores de riesgo de las malformaciones congénitas, se describe la importancia y características del diagnóstico prenatal y de la prevención por medio de la suplementación de ácido fólico en la dieta.

Congenital anomalies in conjunction with intrauterine growth restriction account for 50-60 percent of fetal mortality. This article describes major birth defects by systems; most can be diagnosed by ultrasound while others cannot. Some anomalies develop later in pregnancy and in some cases sonographic examination may suggest the presence of a nonexistent abnormality. Incidence, etiology and risk factors of congenital malformations are described, as well as the importance and characteristics of prenatal diagnosis and prevention through folic acid supplementation in the diet.

Induced spawning and early ontogeny in hatchery-reared catfish Zungaro jahu (Siluriformes: Pimelodidae)

Hatchery-kept catfish jahus Zungaro jahu (Ihering, 1898) were induced to spawn with carp pituitary extract. The telolecithal eggs were round (1.6 ± 0.1 mm in diameter), demersal, free, and covered with a 0.4 mm-thick jelly coat. The gonadosomatic index of 2.8 was comparable to that of other Pimelodidae. The number of eggs x g of ova-1 was 804 ± 144. Hatching occurred 14.5 h after fertilization, at a temperature of 27.3 ± 0.4º C. The newly-hatched embryos measured 3.9-4.3 mm of total length (TL). At 18 h post-hatching (HPH; 5.3 ± 0.1 mm TL), the retina was pigmented, the mouth opened and dorsoflexion of the notochord had initiated. At 36 HPH (6.4 ± 0.2 mm TL), fusiform chromatophores were vertically arranged in the primordial fin fold and the notochord was dorsoflexed. The yolk sac was almost exhausted by 48 HPH (7.3 ± 0.2 mm TL). At 128 HPH (8.6 ± 0.6 mm TL) the pectoral, dorsal, adipose, caudal, anal, and pelvic fins were readily observable whereas the primordial fin fold was no longer visible. At 224 HPH (16.6 ± 2.5 mm TL), the metamorphosis was completed and the larvae had acquired the juvenile appearance.

Jaús Zungaro jahu (Ihering, 1898), mantidos em estação de piscicultura, foram induzidos à reprodução com extrato bruto de hipófise de carpa. Seus ovos são telolécitos, arredondados (1,6 ± 0,1 mm de diâmetro), demersais, livres e cobertos por uma capa gelatinosa com 0,4 mm de espessura. O índice gonadossomático (peso da ova : peso total do peixe) de 2,8 foi semelhante ao de outros Pimelodidae. O número de ovos x g de ova-1 foi 804 ± 144. A eclosão dos embriões ocorreu 14,5 h pós-fertilização à temperatura de 27,3 ± 0,4º C. Os embriões recém-eclodidos apresentaram 3,9-4,3 mm de comprimento total (CT). Dezoito horas pós-eclosão (HPE) e 5,3 ± 0,1 mm CT, a retina estava pigmentada, a boca aberta e a flexão da notocorda tinha se iniciado. Às 36 HPE (6,4 ± 0,2 mm CT), observaram-se cromatóforos fusiformes alinhados verticalmente na nadadeira primordial; a notocorda já se encontrava flexionada. O saco vitelínico encontrava-se quase que inteiramente absorvido às 48 HPE (7,3 ± 0,2 mm CT). Com 128 HPE (8,6 ± 0,6 mm TL), as nadadeiras peitoral, dorsal, adiposa, caudal, anal e pélvica estavam formadas e a nadadeira primordial já havia sido reabsorvida. Com 224 HPE (16,6 ± 2,5 mm CT), a metamorfose se completou e as larvas se transformaram em juvenis.

Morphological Observation on the Prenatal Development of the Human Gastrointestinal Tract

A total of 322 fetuses and 29 embryos were examined light microscopically to evaluate the morphological development of the human gastrointestinal tract with increasing gestational age. The human embryos were analysed by reconstruction of serial section slides. One hundred and forty fetuses ranging from 15 to 41 weeks of gestation were used for correlating the gestational age and the body weight with the measurement of the small and large intestines. 1) The esophagus develps from the distal part of the foregut through a partition of the tracheoesophageal septum. Initially the esophagus is short, but it elongates rapidly and reaches its final relative length and position by the seventh week. The epithelium of the esophagus proliferates and completely obliterates the lumen by the seventh week, but recanalization occurs by the ninth week. The esophageal epithelia consist of three different groups of cells; stratified squamoid cells, ciliated columnar cells and tall columnar cells by the 21th week. 2) The stomach appears as a fusiform enlargement of the caudal part of the esophagus at the fourth week. During next two weeks the stomach acquires its adult shape and final position. The primordial gastric pits and the parietal cells appear at the eighth and eleventh weeks, respectively. 3) As the midgut elongates, it forms a ventral U-shaped loop, called primitive intestinal loop by the fifth week. At this stage the cecum appears as a swelling from the caudal limb of the intestinal loop. By the seventh week the bulks of the caudal limb of the intestine herniate into the umbilical cord, in which the loop rotates 90 degrees counterclockwise around the axis of the superior mesenteric artery. During the tenth week, the intestine returns to the abdomen and undergoes a further 180 degrees counterclockwise rotatation. 4) The cloaca is divided into two parts by a urorectal septum at the fifth week. By the seventh week the urorectal septum has fused with the cloacal membrane, dividing it into a dorsal anal membrane and ventral urogenital membrane. The anal membrane ruptures at the eighth week. 5) During the sixth week the duodenal lumen becomes completely filled with proliferating epithelium. The villi project from the mucosa of the small and large intestines at the eighth and eleventh weeks, respectively. The villi of large intestine become resorbed again after the 21th week. At the fifth week Paneth cells appear through the entire length of the intestine including the rectum, but disappear in the colon and the rectum after the 36th week. 6) The developing Auerbach's plexuses are well recognized along the outside of muscle coat throughout the gastrointestinal tract, but demonstrate no immunoreactivity for the anti-neuron specific enolase antibody. The neuroblasts in the myenteric plexus reveal strong positivity for the anti-neuron specific enolase antibody at the eleventh week, but the ganglion cells differentiate by the fourteenth week. 7) Differentiation of the gastrointestinal wall and development of the myenteric plexus begin form the esophagus and progress caudally down to the colon. But the anorectal wall is differentiated from the cloaca more earlier than the esophagus, stomach and colon are. 8) The small and the large intestines elongate progressively with the increasing gestational age and body weight and increase approximately 5.6 and 5.4 folds, respectively during the 25 weeks from the 15th to 41th week of gestation. At the 40th gestational week the small intestine is 5.68 times the length of the colon. 9) The correlation between the body weight (BW), crown-rump length (CR) and intestianl length (small intestine (SI), large itestine (LI) is presented as: SI (cm)= -33.67 + 4.14CR + 11.62 (BW)(1/3), LI (cm)= 5.56 + 0.76CR + 0.007BW (gm), CR (cm)= 7.82 + 0.015 SI + 0.41 (BW)(1/2).