Muscle spindles were followed in serial transverse sections of freshly frozen rat soleus muscles. Adenosine triphosphatase (ATPase) histochemical staining reaction was used to identify nuclear bagi, nuclear bag2 and nuclear chain intrafusal muscle fibers. Regional differences in ATPase staining occurred along bagi and bag2 fibers but not along chain fibers. Bag1 fibers displayed ultrastructural heterogenity when their intra-and extracapsular regions were compared. Simple "diffuse" and more elaborate "plate" motor nerve terminals were demonstrated histochemically along the poles of bagi and bagl fibers by staining for cholinesterase. One motor terminal of the "plate" appearance was present on a chain fiber pole. There was no consistent spatial correlation between the intensity of regional ATPase staining along the nuclear bag fibers and the location, number and type of motor endings. Other factors, such as intrafusal fiber sensory innervation and regional differences in active and passive functional recruitment of nuclear bag fibers during muscle activity, may contribute to the ATPase staining variability along the intrafusal fibers.

Abundant, highly organized, rod-shaped particles have been found in skeletal-muscle nuclei of two patients with adult-onset rod disease. They were usually single in affected nuclei. Like myofibrillar rods, the nuclear rods consisted of bundles of long, parallel, apparently cross-linked filaments. On longitudinal section the rods had an axial periodicity and in transverse section a wire-mesh appearance. Average periodicities were 189A (nuclear) and 178A (myofibrillar) axially, 180A (both) transversely between the longitudinal rod-filaments on longitudinal-section and cross-section of the rods. Minor differences were that the nuclear rods were slightly lighter stained after osmium-uranyl acetate-lead citrate, lacked thin filaments protruding from their ends, and often were broader. It is proposed that nuclear rods may have a contractile-protein composition and pathokinesis similar to that of myofibrillar rods. Their formation may reflect an epitomization of a newly recognized general biological capability of exogenous, or perhaps endogeneous, nuclear protein alteration.

No abstract

In the present study, we determined circulating serum levels of human placental growth hormone (hPGH) and insulinlike growth factor binding proteins 1 and 3 (IGFBP-1 and IGFBP-3) using two-site radioimmunoassays during the gestational midtrimester of pregnancies affected by chromosomal disorders with the aim of identifying potential marker substances that might have a significant discriminative and predictive value for prenatal diagnosis of fetal chromosomal aberrations and of organ malformations such as neural-tube defect. Our results show that the maternal serum levels of hPGH were significantly elevated in pregnancies affected by chromosomal anomalies or organ malformations as compared with controls. The distribution of IGFBP-1 concentrations for all experimental groups except trisomy 21 were closely similar to the normal population. IGFBP-3 decreased slightly in pregnancies affected by Down syndrome. These findings suggest that hPGH may be useful as an additional marker in prenatal screening for Down syndrome.

Since the first reports of successful pregnancies after treatment with intracytoplasmic sperm injection (ICSI) in humans numerous attempts have been made to assess the genetic risks of this highly invasive technique. During the study period (February 1995-November 96), 142 couples were referred to our genetic counselling unit prior to ICSI. In three couples, genetic counselling revealed a high recurrence risk for a monogenic disease (myotonic dystrophy, hereditary ataxia and polycystic kidney disease). In nine out of 128 men (7%) an abnormal karyotype was identified, including three Robertsonian translocations, two reciprocal translocations, three sex chromosome aberrations and one case with centric fission of chromosome no. 7. A total of 14 men refused chromosomal analysis. Only one of the 122 women examined had an abnormal karyotype (47, XXX). Five out of six men with congenital bilateral absence of the vas deferens (CBAVD) had at least one mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Three had mutations in both CFTR alleles, including one case in which the second mutation was the 5T allele. One patient with CBAVD and a single Delta F508 CFTR mutation also had left renal agenesis. In conclusion, we strongly recommend that genetic counselling, chromosomal analysis and, in the case of CBAVD, screening for CFTR mutations should be offered to all couples with a diagnosis of male or idiopathic infertility.